CAREER: Single-Atom Alloy Catalyst Design for the Electrocatalytic Reduction of Nitrate to Ammonia: Linking Electronic Structure to Geometry and Catalytic Performance

硝酸盐（NO3−）是世界上最普遍存在的地下水污染物之一，严重威胁着人类和生态系统的健康。因此，迫切需要管理工业、食品和水系统中的硝酸盐废物。电催化硝酸还原反应（NO3RR）是一种很有前途的将硝酸转化为有价氨（NH3）的方法。然而，围绕NO3RR的关键科学问题和挑战限制了其实际应用。拟开展的研究重点是通过计算解决多个科学问题，以更好地理解单原子合金催化剂上NO3RR对氨的反应。该项目将研究与密歇根大学自然历史博物馆和华盛顿社区学院合作的教育推广计划相结合，以促进STEM教育和催化培训。建议的研究重点是解决两个科学目标，以提高NO3RR到氨。先前的研究结果表明，NO3RR在过渡金属电催化剂上的最大活性和选择性受到吸附物之间的线性能量标度关系（lsr）的阻碍。第一个科学目标是通过单原子合金（SAAs）电催化剂来回答NO3RR的机理问题，目标是打破这些lsr。SAAs是一类很有前途的催化剂，其中少量孤立的金属原子存在于金属宿主的表层。然而，SAAs几乎没有被用于NO3RR。使用最先进的大正则密度泛函理论，我们将测试以下假设：1)明智选择的SAAs将打破限制NO3RR在纯金属上活性的lsr， 2)淬灭N-N耦合以支持NH3选择性。第二个科学目标旨在阐明SAAs的几何和电子结构如何与NO3RR活性和选择性联系起来。这些见解将有助于设计SAA催化剂，以破坏NO3RR的lsr。本研究的预期结果是对SAAs及其破坏NO3RR的lsr的能力的新的机制理解，将其性质与反应性联系起来的SAAs设计规则，以及对溶剂和应用电化学电位在NO3RR上的作用的一般见解。拟议的教育活动是：(i)设立一个“研究站”博物馆展览，向公众讲授催化作用和硝酸盐问题；（二）开展中学生暑期科学研究活动；（iii）通过科学传播研究员计划进行科学传播的教学和实践；（四）担任第一代社区学院学生的暑期研究导师。拟议的综合研究和教育活动将支持多学科研究培训，增强STEM的公平性、多样性和包容性，并提高美国的经济竞争力。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nitrate (NO3−) is among the most ubiquitous groundwater pollutants in the world and a serious threat to human and ecosystem health. Thus, there is a compelling need to manage nitrate waste across industry, food, and water systems. The electrocatalytic nitrate reduction reaction (NO3RR) is a promising approach to convert nitrate into valuable ammonia (NH3); however, critical scientific questions and challenges surrounding NO3RR limit its practical use. The proposed research focuses on computationally addressing multiple scientific questions to better understand NO3RR to ammonia on single atom alloy catalysts. This project integrates the research with an educational outreach plan in collaboration with the Museum of Natural History at the University of Michigan and the Washtenaw Community College to promote STEM education and catalysis training.The proposed research focuses on addressing two scientific objectives to enhance NO3RR to ammonia. Prior results showed that the maximum NO3RR activity and selectivity on transition metal electrocatalysts is hindered by linear energy scaling relations (LSRs) between adsorbates. The 1st scientific objective aims to answer mechanistic questions of NO3RR by single-atom alloy (SAAs) electrocatalysts, with the goal to break these LSRs. SAAs are a promising class of catalysts in which small amounts of isolated metal atoms are present in the surface layer of a metal host. Yet SAAs have hardly been explored for NO3RR. Using state-of-the-art Grand Canonical Density Functional Theory, we will test the hypotheses that 1) judiciously selected SAAs will break LSRs that limit NO3RR activity on pure metals, and 2) quench N-N coupling to favor NH3 selectivity. The second scientific objective aims to elucidate how geometry and electronic structure of SAAs link to NO3RR activity and selectivity. These insights will help design SAA catalysts that break LSRs for NO3RR. The expected outcomes of this research are new mechanistic understanding of SAAs and their ability to break LSRs for NO3RR, design rules for SAAs that link their properties to reactivity, and general insights into the role of solvent and applied electrochemical potential on NO3RR. The proposed educational activities are: (i) Creating a “Research Station” museum exhibit that will teach the public about catalysis and the nitrate problem; (ii) Engaging middle school students through a summer science research program; (iii) Teaching and practicing science communication through a Science Communication Fellows Program; and (iv) Serving as summer research mentors to first-generation Community College students. The proposed integrated research and educational activities will support multidisciplinary research training, enhance STEM equity, diversity and inclusion, and increase USA economic competitiveness.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.